The present invention relates to a recording medium and a system for recording and reproducing the recording medium, and more particularly to a recording medium having a logical data structure for recording and reproducing information, the recording modes of which varies.
There has been known the DVD-Video, which is an optical read-only disc capable of storing high-quality video information and audio information. The DVD-Video records information based on a specific logical data structure so as to be applied in an extensive field and to have various functions enabling various interactive reproduction thereof.
In accordance with the logical data structure, which is disclosed in known documents, the DVD-Video comprises a lead-in area at the inner end portion of the disc, lead-out area at the outer end portion, and a data recording area between the lead-in and lead-out areas wherein a plurality of data files are stored.
The data which is recorded in the data recording area can be roughly divided into presentation data to be reproduced and navigation data for controlling the reproduction. The navigation data includes attribute of the presentation data and control data necessary for the reproduction. There are five navigation data, which are video manager information (VMGI), video title set information (VTSI), program chain information (PGCI), presentation control information (PCI), and data search information (DSI).
The presentation data comprises video data, audio data and subpicture data which are integrated together with a part of the navigation data in accordance with the MPEG 2 standard (ISO 13818-1).
The video data has one stream of data compressed in accordance with the MPEG 2 video format (ISO 13818-2). The audio data take up a maximum of eight streams and comply with in one of the linear PCM, AC-3 and MPEG audio standards.
The subpicture data are data compressed in accordance with the run-length coding for enabling menus, and credits and words in the case of movies and karaoke system to be displayed over the main image, and take up a maximum of 32 streams.
These video data, audio data, and subpicture data are aggregated into sets in pack unit so as to form a bit stream multiplexed in plurality of pack units, thereby forming the presentation data.
The presentation control information (PCI) and data search information (DSI) are added to each of the video data, audio data and subpicture data to form a video object unit (VOBU).
The presentation control information (PCI) is provided for determining the reproduction information in accordance with the condition of the presentation data. The data search information (DSI) relates to fast forward and rearward reproductions and continual reproduction.
A plurality of video object units (VOBU) form a cell (CELL), and a plurality of cells (CELL) form a video object (VOB), and a plurality of video objects (VOB) form a video object set (VOBS).
The video title set information (VTSI) and the program chain information (PGCI) are added to one or more video object set (VOBS) to form a video title set (VTS). A plurality of video title sets (VTS) are recorded sequentially after control data called video manager (VMG) having video manager information (VMGI).
The video title set information has attribute information of the video object set (VOBS) in the video title set (VTS). The program chain information (PGCI) has information on reproducing order of the presentation data in the form of information on order of the cells (CELL). The video manager information (VMGI) has information on the directory of the video title set (VTS).
The reproduction of the presentation data is controlled in accordance with the information of the navigation data so as to enable the interactive reproduction.
The DVD-RW (rewritable) has also become to attract attention in addition to the DVD-Video. The DVD-RW belongs to the same so-called DVD family including the DVD-Video, and has the physical compatibility therewith. Since the DVD-RW is capable of recording, reproducing, erasing and rewriting information, it is a recording medium extremely suitable to the user for producing or authoring a desirable multimedia title.
However, if the logical data structure for the DVD-Video is simply adapted to DVD-R and DVD-RW, since various types of information are now recorded, there occur problems.
In the DVD-Video, there is provided a stereophonic recording mode called 2/0 mode wherein 2-channel audio data are recorded as one audio stream, and a monaural recording mode called 1/0 mode wherein a monaural audio data are recorded as one audio stream.
However, when recording a movie which is bilingually broadcast, the bilingual speech and stereophonic sound are frequently alternately changed. Namely, audio information to be recorded includes individual information in multiple languages, each having the same time base, hereinafter referred to as multiplexed information, and multi-channel information such as the stereophonic audio information, hereinafter referred to as multi-channel information. In order to record a television program having such audio information, each time the type of the audio information changes, the audio stream is changed between the stereophonic recording mode to monaural recording mode, so that the video object (VOB) must be freshly set.
More particularly, at a bilingual broadcast, the monaural recording mode is selected so that a main sound and a sub sound are each recorded in a separate stream, thereby using two streams. At a stereophonic broadcast, the stereophonic recording mode is selected so that one stream is used. Every time the recording mode changes, a new video object is required. The same procedure is necessary when the bilingual speech and the monaural sound are alternately changed.
When the information is thus recorded, changing over the audio stream, the audio stream must also be changed when reproducing the information. When changing the stream at the reproduction, noises may generate, or a silent period may occur, thereby causing deterioration in sound quality.
In addition, if the reproduced digital audio data is supplied to a conventional digitally input audio-visual device, each time the audio stream is changed, the reproduction mode must be changed between the stereophonic reproduction mode and monaural reproduction mode.